One Dimension - Constant Velocity and Constant acceleration [Physics demonstration]

Using a glider on an air track we can see what constant acceleration in one dimension looks like and what constant velocity looks like.
Constant velocity: Use the glider to check that the air track is level. Two independent photogates are used to detect the interrupt time in ms. The average velocity is Δx/Δt, where Δx is the length of the glider. The velocities are nearly the same for the two locations.
Constant acceleration: The air track is now tilted a small amount. Now there must be an acceleration, because the glider gains velocity if it is released from rest. It is reasonable, and we will show in dynamics, that the acceleration constant here.
Hence, x = at2/2 for v0 = 0 and x0 = 0, so x(t) is an upright parabola with vertex at the origin; that is x ∝ t2